Hydrothermal evolution and source of metallogenic materials of Beiya Au polymetallic deposit,western Yunnan,China

The Beiya porphyry-skarn gold-polymetallic deposit is one of the largest gold deposits in China and it also contains significant amounts of silver and base metals.The ore-bearing monzonitic granite porphyry occurs as a stock,of which the skarn type gold-copper-iron ore bodies are controlled by the contact zone between alkali-rich monzonitic granite porphyry and the limestone,and the gold-silver polymetallic mineralization is controlled by interlayer structure.Alteration and mineralization occur around the intrusion and exterior of monzonitic granite porphyry.Ore mineral formation sequence is as follows:skarn minerals→magnetite→pyrite→chalcopyrite/bornite+pyrite+gold→pyrite+galena+gold(silver).Petrographic studies of fluid inclusions indicate that the following types of inclusions exist in the pre-mineralization quartz-pyrite stage:gas-liquid two-phase inclusions(L-type),three-phase inclusions with daughter minerals(D-type)and gas-rich inclusions(V-type).The colorless transparent quartz in the main gold-chalcopyrite-pyrite stage mainly consists of L-type and V-type inclusions,whereas the inclusions in the late gold-silver-galena stage are mainly L-type.The evolution of ore-forming fluids shows a trend from high temperature,high salinity to medium-low temperature and low salinity.Medium-low density fluids play a dominant role in mineral component migration and transportation.Fluid cooling and boiling are the main mechanisms of gold-copper precipitation,while the involvement of atmospheric water and pH reduction are the main mechanisms of gold-silver polymetallic precipitation.The fluids in the quartz-pyrite stage before mineralization and the main gold-chalcopyrite-pyrite stage are dominated by magmatic water,while in the gold-silver-galena stage the fluids are dominated by atmospheric water.Isotope tracers show that S and Pb are mainly derived from monzonitic granite porphyry,not from limestone of the Beiya Formation.     

Zircon U-Pb geochronology and Hf isotopic constraints on petrogenesis of Carnian Huanglonggou granodiorites in Wulonggou area of Eastern Kunlun Orogen,NW China

The Wulonggou area located in the Eastern Kunlun Orogen in NW China is characterized by extensive granitoid magmatism,ductile faulting and orogenic gold mineralization.The Huanglonggou granodiorite is cut by an orogenic gold-bearing fault.This study investigated the major and trace-element compositions,zircon U-Pb dates and zircon Hf isotopic compositions of the Huanglonggou granodiorite.One Huanglonggou granodiorite sample yielded a weighted mean U-Pb zircon age of~221 Ma(Carnian).The Carnian granodiorite is metaluminous,with high alkalis contents of 6.37%--8.86%,high Al_2O_3contents of 15.41%--16.19%,high Sr contents of(426--475)×10~(-6),relatively high Sr/Y ratios,high(La/Yb)_Nvalues and low HREE,suggesting an adakite type high-Si O_2granite.The Huanglonggou granodiorite sample has zirconε_(Hf)(t)values ranging from-4.4 to+1.1.These Hf isotopic data suggest that the Carnian granodiorite was likely derived from the partial melting of subducted Paleo-Tethys oceanic slab.It is suggested that the Late Triassic granodiorite was emplaced during the northward subduction of Paleo-Tethys oceanic slab.Orogenic gold mineralization in the Wulonggou area formed after the emplacement of the Late Triassic intrusive rocks.     

Expansion of Juniperus sibirica Burgsd. as a response to climate change and associated effect on mountain tundra vegetation in the Northern Urals

Shrub expansion into arctic and alpine tundra is one of the prominent vegetation changes currently underway. We studied the expansion of shrub vegetation into high elevation tundra in the Kvarkush Range of the Northern Ural mountains, Russia. Age structure analysis of the dominant shrub Juniperus sibirica Burgsd. seems to support ongoing upslope advance of shrubs, a process particularly active in the second half of the 20 th century. We found a close connection between the expansion of shrub vegetation and the general change in climatic conditions of the cold season(months with mean airtemperature below 0°С from November to March). In general, the greatest influence on the distribution of J. sibirica is exerted by the climate conditions of the beginning(November-January) and the end(March) of the cold season. With increasing elevation, the correlation coefficients between the establishment of J. sibirica shrubs and the precipitation of the beginning of the cold season increased, and reached maximum values at the top elevation level of the study area. However, the upwards shift of J. sibirica into typical mountain tundra does not lead to changes in the ecological structure of vegetation at this stage, but simply a decrease in the area of mountain tundra.     

胶北地块与金矿有关的花岗岩类的研究---第一章 胶北地块的地质发展史

Jiaobei block is well known as rich in gold mineral resources. The gold mineralization is closely related to granitoids, but there are different views about the age of granits and the type of granitoids with which gold mineralization is associated. Based on the study of petrology, mineralogy, geochemistry and isotopic geology of the granitoids, enclaves and viens in this region, some conclusions are obtained.     

Geological characteristics and metallogenic prognosis of main gold deposit in Altai gold ore belt, Xinjiang

Altai polymetallic mineralization belt is famous copper-polymetallic mineralization belt in the world. There are a lot of gold deposits in the Altai ore belt in Xinjiang, China. These gold deposits belong to two genetic types: volcanogene late-stage hydrothermal type and fractured altered rock type. The authors discuss mainly the geological and mineralized features of fractured altered rock type of gold deposits in Altai gold ore belt. Base on this study, the metallogeniC law is summarized and the deep metallogenic prognosis has been done in Duolanasayi and Tuokuzibayi gold deposits, and some mineralized anomalys have been discovered.     

Distribution of heavy metals and nutrients in rainwater in coastal regions between the southern Yellow Sea and East China Sea

Rainwater samples were collected in series in Qianliyan Island (southern Yellow Sea) and Shengsi Archipelago (East China Sea) between May 2000 and May 2002, chemical analysis for pH values,concentrations of heavy metals (Cu, Pb, Zn and Cd) and nutrients (NH4^-, NO3^-, PO43^-, SiO32^-) were performed.Results indicate that concentrations of most of the heavy metals and nutrients in rainwater show clear seasonal variation, i.e. high level in winter and low level in summer. Regionally, concentrations are higher in the southern Yellow Sea than in the East China Sea, but the annual input of heavy metals into oceans by wet deposition is similar in both stations. However, the input of nutrients by wet deposition in the East China Sea is 2-3 times higher than that in the southern Yellow Sea. In individual, Pb and PO4^3- are input to the sea mainly by dry deposition; whereas Cu, Zn, Cd and N compounds are input dominantly by wet deposition, the N/P ratios in the rainwater from two stations are much higher than those in seawater, showing a significant impact of atmospheric wet deposition on marine production and biogeochemical circulation of nutrients in these sea regions.     

Linking Monsoon Activity with River-Derived Sediments Deposition in the Northern South China Sea

The history of the East Asian monsoon(EAM) since Last Glacial Maximum is reconstructed based on records in a sediment core retrieved from the northern South China Sea. The provenance of organic carbon and the EAM's evolution are investigated using combined organic carbon, grain size, and AMS 14 C dating analysis. Responding to the strong winter monsoon, the marine organic matter was dominated in the sediments, and δ13 C of organic matter was high during the last glacial period. During the Holocene, the primary productivity decreased and the dilution effect of riverine inorganic clastics strengthened. Accordingly, the total organic carbon contents and δ13 C values decreased, and terrestrial organic matter content increased in the core sediments. The 4 μm grain size fraction, as the environmental sensitive grain size component, is determined to reconstruct the paleoclimatic records. During the last glacial period, the contents of 4 μm grain size component were mainly controlled by the sea level changes. Upon the Holocene, the influence of the sea level changes weakened and the roles of current system and provenance strengthened. The correlation between the EAM and solar insolation forcing is also discussed in this paper.     

Mineral occurrence for Dachang gold deposit and its impact on gold recovery rate in Qumarleb County,Qinghai

Based on X-ray diffraction, optical microscopy and scanning electron microscopy analysis of the Dachang gold ore, it is showed that the sulfide of ore is the main carrier minerals of gold. A majority of gold is embedded in pyrite and tetrahedrite as the form of inclusion and a small amount intergrowth with pyrite and gangue mineral, occasionally the presence is in form of monomer natural gold. The main factors which influence the recovery rate are sulfide mineral particle size, and the fine grained sulfide is beneficial for the dissociation and flotation of gold bearing minerals. The monomer dissociation degree of gold bearing minerals can reach 91.3% , when the grinding fineness is less than 0. 074 mm and grain level accounts as 80%. It is not conducive to the flotation of sulfide if the grinding fineness is low or high. It is difficult to completely dissociate the monomer if there is a small amount of pyrite and arsenopyrite in the ore. Therefore, before leaching the gold, it must conduct pretreatment to reach the ideal recovery rate of the gold, like roasting oxidation, pressure oxidation and biological oxidation. The fine microscopic gold has little influence on the gold recovery rate.     

Geological structure, composition of ores and age of the Bamsk gold deposit, Amur region, Russia

The Bamsk gold-ore deposit is located in the Amur region, the Far East of Russia. It is confined to the Early Cretaceous volcanicoplutonic uplift of central type, located in the Stanov folded-clumpy Pre-Cambrian system. The deposit is presented by a series of gold-bearing quartz and carbonate-quartz vein-stringer zones. They are confined to the super-intrusive zone of the Nevachansk subvolcanic intrusion of sienite-porphyric composition. The mineralization is being controlled by zone of fractures developed in the autochthone of the Bamsk fault. Quartz, carbonates and sericite prevail in the composition of ores. The quantity of ore minerals doesn‘t exceed 1% ～ 5%. Pyrite, chalcopyrite, galena and native gold are widely spread, Sheelite, gold and silver tellurides, sulphobismuthites, acanthite, sphalerite and cinnabar are less developed. Four stages of mineralization have been distinguished. Gold-sulphide-sulphosalt ore with tellurides of gold and silver is productive for gold. The following set of elements is typomorphic for the ores of the deposit: Au, Ag, Cu, Bi, Mo, Pb and Sb (W1, Pb1, Mo) -Cu- (Ag, Bi, Sb, Mn, W2,, Pb2) form the vertical series of zoning. Rocks, enclosing the mineralization are exposed to the processes of listvenitization-beresitization. The processes of gumbeization and argillization are less manifested. The age of the gold mineralization, determined by Rb-Sr method on ore-accompanying minerals, is 130.6 Ma.     

Geological and geochemical prediction on deeply-seated ore-bodies in Haigou gold deposit of Jilin,China

Lode 28 is the largest gold-bearing quartz vein in Haigou gold deposit,and the lode itself contains more than 30t of gold. Geochemical study shows that 12 trace elements related gold mineralization can be divided into 5 metallogenic factors(element assemblages) .The high values of F1,F2 and F4 together indicate overlapped of multiple stages of gold mineralization,revealing high potential of gold mineralization at depth;the single high value of F4 represents the root of an existing ore body while high values...     

东昆仑东段中-晚三叠世区域岩浆-热液成矿系统

东昆仑成矿带在早中生代发生了大规模的成矿作用,形成了一系列脉状金矿床、脉状银铅锌矿床、斑岩型铜钼矿床和矽卡岩型铁多金属矿床,但这些矿床之间的成因联系尚不清楚。东昆仑东段以其多样的矿床类型为这一科学问题的研究提供了理想场所。在总结归纳东昆仑东段主要类型矿床时空分布和地质特征的基础上,通过系统分析各类矿床的成矿时代、成矿构造背景及成矿流体与物质来源,探讨它们之间的成因联系。研究结果显示,东昆仑东段各类矿床主要形成于中-晚三叠世(240~220 Ma),均是东昆仑古特提斯陆陆碰撞及后碰撞伸展作用的产物。此外,区内及外围东昆北地体中的各类矿床均具有相似的成矿流体与成矿物质来源,且与该时期广泛发育的深部岩浆作用密切相关,共同组成了一个巨型的岩浆-热液成矿系统,不同类型的矿化可能是该岩浆-热液系统不同演化阶段的产物。巴颜喀拉板块深俯冲及板块断离诱发软流圈地幔的上涌及随后的大规模岩浆-流体活动,富含金属挥发分的岩浆热液与上地壳的岩石和流体发生交代和流体混合,最终形成区内巨型的岩浆-热液成矿系统。基于该成矿系统,东昆仑东段具有寻找多类型共生矿床的潜力。      

Geochemistry and metallogenic age of Sishanlinchang gold-silver deposit in Jidong of Heilongjiang

the Sishanlinchang gold-silver deposit is mainly composed of gold-quartz vein type ores.It has many kinds of sulfides and gold in high grade.The Au has a close correlation with As,Pb,Ag and Cu.Geochemically,the deposit is characterized by relatively enrichment in LREE with moderate or lower Eu negative anomaly.Sulfur isotopes appear as single and deep source,and lead isotopes indicate the Pb is from the earth’s mantle and crust,which mainly are orogenic belt Pb,the ore-forming fluid has a temperature of 215℃-350℃ and a low salinity with a mixture of characteristics of magmaitc hydrothermal and meteoric water.The ore-forming age is 111.1-111.4 Ma.The deposit is formed in mineralization and precipitation of metallogenic materials caused by the mixture of the magmatic hydrothermal fluid and meteoric water.     

对遂昌治岭头金矿的几点看法

治岭头金矿在构造研究,成矿及其时代等问题,一直存在不同看法,90年代前绝大多数同志认为,该处属较老时代的金矿。目前已由不同阶段成矿到与火山热液及地下热水成矿有关的几种较年青金矿的看法。本文从构造分析、火山周边断裂矿化及矿石绝对年龄样成果,提出该区金矿与火山热液关系的密切,成矿时代属燕山晚期（相当中下白垩世）。     

璜山金矿找矿模式及应用

诸暨璜山金矿是除治岭头以外浙江省第二金矿,它的找矿模式为"三高两低一复合"的找矿模式,即高金晕、高极化率、高磁场跳跃、低电阻率、低电位和北东断裂与北东东断裂复合处是成矿最有利部位.在其附近仍有类似成矿部位,有望扩大远景.     

桂西北微细粒浸染型金矿成矿作用分析

自1985年在桂西北中三叠统浊积岩中发现微细粒浸染型金矿以来,该区己受到世人所瞩目。本文在简介区域地质背景与矿床地质特征的基础上,侧重于金矿成矿作用分析。通过对成矿的三源(矿源、水源、热源)、构造(导矿、容矿)、物理—化学条件与运移—沉淀机制和成矿过程分析等,得出中三叠统浊积岩系为容矿岩系之一,而非矿源岩,成矿时基底存在区域岩浆热液活动的认识;并指出在求取元素丰度值过程中所剔除异常值性质的判断时,采用了柯氏正态检验法、岩石孔渗性、镜质组反射率与牙形石色变指数等研究方法的成果。还探讨了右江浊积岩盆地与成矿作用之间的关系、产金层位分带性变化原因。     

胶东乳山金矿区原生晕地球化学特征及深部成矿预测

英格庄金矿以相对富As、Co、Ni而三甲和铜锡山金矿则以相对富Cu、Pb、Zn、Ag为特征.聚类分析显示,英格庄金矿具Bi+Hg、As+Sb+Co与Pb+Zn组合,三甲金矿具Bi+Hg+As+Sb+Co、Pb+Zn与Ag+Cu+Au组合,而铜锡山金矿则显示Bi+Hg+Sb+Pb+Ag、Cu+Au+Zn+As及Mo+Ni组合.结合Ni、Co、Mo与Ag、Hg、As、Sb等的相关特征,认为上述三个金矿均有成矿头尾晕叠加现象.Au、Ag、Cu、Pb、Zn、As、Sb、Bi、Hg、Mo等元素垂向变化规律显示,英格庄金矿在-200m标高以下、三甲金矿在-500m标高以下尚有成矿富集段存在.其中,所确定的英格庄金矿的靶位在16勘探线附近,三甲金矿的靶位则在16～20勘探线间.     

Zircon U-Pb age,geochemical and Nd isotopic data of Middle Jurassic high-Mg dioritic dike in Liaodong Peninsula,NE China

Zircon LA-ICP-MS U-Pb age, geochemical and Nd isotopic data are presented for a newly recognized high-Mg dioritic dike from Haicheng, Liaodong Peninsula, NE China, to constrain its petrogenesis. The zircons from the high-Mg diorite exhibit striped absorption and oscillatory growth zoning in the cathodoluminescence （CL） images, and have high Th/U ratios （0. 05-0.9）, indicating a magma origin. Zircon LA-ICP-MS U-Pb dating indicates that 206pb/238U ages of 12 spots of zircons are between 167 Ma and 178 Ma, yielding a weighted mean 206pb/238U age of 172 ＋ 2 Ma （MSWD =4. 1 ）, which represents the forming age of the high-Mg dioritic dike, i. e. Middle Jurassic. Geochemically, the samples have SiO2 =55.4-60. 6 wt. % , Na20 =2. 2-2.76 wt. % , K20 = 1.32-2. 02 wt. % and （Na2O ＋ K2O） =3.82--4. 47 wt. %, belonging to sub-alkaline series and displaying a calc-alkaline evolutionary trend. They are characterized by high MgO （4. 75-6.85 wt. % ）, Mg# （55-61）, Cr（130-262 ppm）, Ni（63-130 ppm）, Sr（568-857 ppm）, and Ba（484-1 130 ppm） contents, with geochemical features analogous to those of high-Mg adakites. They show variable end （t） values （ - 1.3 to - 3.9） , with a weighted value of - 2. 7, which plot intermediately between the field of the ancient continental crust and the depleted mantle source, indicating that both the lower crust and mantle source are necessary for the generation of the parent magma of the Haicheng high-Mg diorites. The Haicheng high-Mg dioritic dike in the Liaodong Peninsula and the Jurassic magmatism in the eastern North China Craton formed under a continental crustal thickening setting that may be related to subduction of the Paleo-Pacific oceanic plate.